suloh

Just wondering how to test brake calipers. I am installing brand new rotors and pads (Original Lexus Parts) and would not like a bad/sticking caliper to destroy the new rotors.

I have turned the wheel and it turns fine but I suspect that the pads are just touching the rotors very lightly. Is that normal? Are the pads supposed to totally not touch the rotors at all? Not to sure how auto brakes worn. On my bicycle, when brakes are released, the rubber brake pad does not touch the rims.

I removed the calipers and did not notice any leakings at all. I did notice that the rubber cap on the bleeder nut is broken and brittle.

bob2200

I don't consider myself a brake expert, but I can say that car calipers don't have/need a spring return like normal bicycle brakes. (I don't know about bicycle disk brakes, but they might not have a spring return either). The normal position for auto disk brake pads is riding just above the rotor surface. If it the rotor spins freely, I don't think there is sticking.

The best was to test for sticking is to see if the brakes pull to one side when braking. Unusual brake pad wear is a clue too.

The rubber cap on the bleeder is just a dust cap and I wouldn't worry about it being brittle. Any replacment would be for cosmetic reasons. There's a good chance that the rubber dust cap is not Lexus/Toyota specific.

suloh

This means that pads actually gently touch the rotors. (In my car, I can quite easily spin the wheel with my hand). But I can hear the pad touching the rotors when I spin the wheel by hand. It is just a soft rubbing sound of the pad touch the rotors.

meZoom!

Visually, the pads are touching the rotors. The amount of "force" being applied is controlled by fluid, which is why your vehicle has brake fluid, and your bicycle does not (the force is in the hand grip).
On a bad or sticking caliper, you should compare the wear of the old pads you removed, and you can also compare left to the right. Excessively sticking calipers will produce uneven wear between the left and right sides (unless for some miraculous reason they are sticking the same). If the inner and outer pads are wearing slightly at different rates, don't worry. You can also tell if the pad seems burnt or scorched.

T0ked

iTrader: (2)

From what I've read previously, the pads are supposed to float over the rotors. I don't think there is anything that really pulls the pads back except for the 2 spring clip things that attach to the pads. As long as the rotors spin freely, should be fine. The real test is when you're driving, check pad wear and for any burnt brake smells.

mtsao

Somthing else you should do is to make sure to clean any rust and/or debris from the metal surfaces upon which the brake pads will rest. After these surfaces are cleaned, you can also apply some silicone brake lubricant on these same surfaces--this will lessen the friction between the pads and the torque plate, allowing the pad to back off more easily when the brakes are released.

Also, visually inspect the boot that sits at the base of the brake caliper piston. If this boot is torn or not seated properly, it can allow debris and other contaminants to enter the cylinder and over time, this will likely cause the piston to 'stick'.

suloh

OK. I have finished installing new rotors and pads (all bought from the dealer). Both the wheels seem to spin quite freely. I am changing both the rotors and brakes because of heavy vibrations when braking from 80 to 60 mph. Also when I bought the car, the front right tire was badly worn out especially on the right shoulder and car pulled to the right.

I took the car for a short drive after the new brakes. Car still pulls to the right even though alignment says everything is ok. Front tires are brand new and balanced, Rotors and Pads are brand new.

Someone suggested touching the rims after a short drive and guess what? The left front rim (driver's side) feels a lot warmer than the right rim. Perhaps the driver's side caliper is sticking?? But if left hand front caliper is stick, wont the car pull to the left??

As my rotors and pads are new, I would like to solve the problem before I warp the new rotors.

Any suggestions on what I should do? Will contaminated brake fluid cause claiper to stick? When I removed the two shims from the old brake pads, there appears to be glue on the shims, is this normal? I did not notice any leaking brake fluid.

bob2200

I think the test is to coast to a stop from highway speed without using the brakes and then feel the rims. Did you try that? They should then both be cold.

If it's dry, it is probably a plastic membrane material that is applied as a paste and then dries, and is used to dampen any vibration that can cause noise when braking.

suloh

Will give the coast to a stop method a try. I guess that will tell if I have a sticking caliper.

koolaidman

no they are not supposed to touch. there is a square cut rubber arround the piston witch is supposed to automaticly adjust brake pad free play.

let me ask u a question before ur last brake job did u knowtice a huge ammount of different in pad wear. i ask this for a siezed caliper 1 side will look almost brand new and the other will be excessivly worn out.